Real-Time Experimental Benchmarking of Control Strategies for a Coupled 2-DOF Helicopter

This paper presents a real-time experimental comparison of four control strategies—PID, Fractional-Order PID (FOPID), Fuzzy PID/PD, and Model-Free Control (MFC)—applied to trajectory tracking of a coupled 2-DOF Quanser Aero 2 helicopter. A linear MIMO model is identified to support controller design, and all approaches are evaluated under three operating conditions: coupled dynamics, static decoupling, and dynamic decoupling. Experimental performance is assessed using Integral Square Error, control effort, overshoot, and settling time metrics implemented on the QUARC real-time platform. The results show that interaction mitigation affects control performance. Static decoupling improves tracking accuracy, while dynamic decoupling reduces cross-coupling effects at the expense of increased noise sensitivity. Among the evaluated controllers, the Fuzzy PID/PD strategy achieves the best overall balance between tracking performance and control effort, whereas Model-Free Control provides smoother actuator behavior. The study offers practical experimental guidelines for selecting control strategies in coupled UAV systems.